The method according to the preamble is known in the field and is described in, among others, the American patent application U.S. Pat. No. 4,971,840. The known method is used to dry wood, wherein the temperature of the liquid is held just above 100° C. At this temperature the water will drain out of the wood, after which wood remains after a time with a water percentage of less than 5%. The known method can also be used to thermally modify the wood, wherein the wood can optionally be first dried with the known method. The thermal modification takes place by subjecting the wood to a temperature between 130° C. and 220° C., wherein it is important that the wood be placed in a low-oxygen environment.
Known applications for the method are: drying firewood, modelling a wooden part in for instance a chair seat, and producing sustainable wood as substitute for hardwood which is used, among other purposes, as garden timber and facade cladding.
The known method has the advantage that the method entails the wooden parts being placed in a low-oxygen environment. There is hereby no danger that the wooden parts will combust during the thermal modification.
The known method has the drawback that the liquid is absorbed by the wood. The treated wood can hereby not be painted and so is certainly not suitable for use as door/window frame wood.
If the treated wood lies in the outside air there is also a chance of the liquid draining out of the wood. In many cases a liquid is used which is solidified at room temperature, such as paraffin. Once the paraffin has drained out of the wood and then solidified, dirt may begin to adhere thereto.